<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<body>

  <div id="app">
    姓：<input type="text" v-model="firstname"><br>
    名：<input type="text" v-model="lastname"><br>
    <p>姓名：{{ totalname }}</p>
    <button @click="changename">修改姓名</button>
  </div>
  <script src="https://cdn.jsdelivr.net/npm/vue@2/dist/vue.js"></script>
  <script>
    const app = new Vue({
      el: '#app',
      data: {
        firstname:"",
        lastname:""
      },
      computed: {
        // 简写
        // totalname(){
        //   return this.firstname + this.lastname
        // }
        // 完整写法
        totalname:{
          // 获取
          get(){
            return this.firstname + this.lastname
          },
          // 修改
          set(value){
            console.log('修改--totalname被重新赋值',value);
            this.firstname = value.slice(0,1)
            this.lastname = value.slice(1)
          }
        }
      },
      methods: {
        changename(){
          this.totalname = "符离"
        }
      }
    })
  </script>
</body>
</html>